This invention generally relates to electronic systems and in particular it relates to an auxiliary boundary regulator that provides enhanced transient response.
There are a number of ways to accomplish a voltage regulation function, but two are more commonly used: (1) a continuous-time analog regulator or switched mode power supply (SMPS) with a continuous-time control loop, and (2) a xe2x80x98hystereticxe2x80x99 type of converter which simply responds to provide energy when the regulated output falls outside of a hysteretic window. The first type provides a tightly controlled, lowripple, output voltage, and in the case of the SMPS, a controlled operating frequency, but the transient response time is slow. A fast load or supply transient can send the output out of regulation limits before the control loop can respond. The second type has a large ripple voltage and uncontrolled frequency, but the response time is extremely fast.
One prior art device involves the use of a linear regulator to perform the boundary function about an SMPS main converter. Another prior art device involves using a similar fast recovery converter around the main converter, which is an SMPS.
A regulator circuit with an auxiliary boundary regulator that provides enhanced transient response includes: an upper comparator having a first input coupled to a feedback node and a second input coupled to a first reference voltage node; a lower comparator having a first input coupled to the feedback node and a second input coupled to a second reference voltage node; a first switching device having a control node coupled to an output of the upper comparator; a second switching device having a control node coupled to an output of the lower comparator; an inductor having a first end coupled to the first and second switching devices, and a second end coupled to an output node; and a feedback circuit coupled between the output node and the feedback node. This circuit provides a precise, quiet, linear regulator that provides a tightly regulated output with a fast regulator working in parallel to ensure that the output voltage stays within an acceptable boundary.